Effective Field Theory and Unitarity in Vector Boson Scattering

TL;DR

This paper introduces a unitarization method for effective field theories in vector boson scattering, enabling accurate high-energy predictions and accommodating strongly-coupled models at the LHC.

Contribution

It presents a parameter-free T-matrix unitarization approach that extends EFT validity to high energies and includes effects of resonances and higher-dimensional operators.

Findings

Unitarized framework provides consistent high-energy vector boson scattering predictions.

Dimension-8 operators can dominate in strongly-coupled models like composite Higgs.

Inclusion of tensor and scalar resonances enhances model realism.

Abstract

Weak vector boson scattering at high energies will be one of the key measurements in current and upcoming LHC runs. It is most sensitive to any new physics associated with electroweak symmetry breaking. However, a conventional EFT analysis will fail at high energies. To address this problem, we present a parameter-free prescription valid for arbitrary perturbative and non-perturbative models: the T-matrix unitarization. We describe its implementation as an asymptotically consistent reference model matched to the low-energy effective theory. We show examples of typical observables of vector-boson scattering at the LHC in our unitarized framework. For many strongly-coupled models like composite Higgs models, dimension-8 operators might be actually the leading operators. In addition to those longitudinal and transversal dimension eight EFT operators, the effects of generic tensor and scalar resonances within simplified models are considered.